How to properly import a selfsigned certificate into Java keystore that is available to all Java applications by default?

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Problem :

I do want to import a self signed certificate into Java so any Java application that will try to establish a SSL connection will trust this certificate.

So far, I managed to import it in

keytool -import -trustcacerts -noprompt -storepass changeit -alias $REMHOST -file $REMHOST.pem
keytool -import -trustcacerts -noprompt -keystore cacerts -storepass changeit -alias $REMHOST -file $REMHOST.pem

Still, when I try to run HTTPSClient.class I still get: PKIX path building failed: unable to find valid certification path to requested target

Solution :

On Windows the easiest way is to use the program portecle.

  1. Download and install portecle.
  2. First make 100% sure you know which JRE or JDK is being used to run your program. On a 64 bit Windows 7 there could be quite a few JREs. Process Explorer can help you with this or you can use: System.out.println(System.getProperty("java.home"));
  3. Copy the file JAVA_HOMElibsecuritycacerts to another folder.
  4. In Portecle click File > Open Keystore File
  5. Select the cacerts file
  6. Enter this password: changeit
  7. Click Tools > Import Trusted Certificate
  8. Browse for the file mycertificate.pem
  9. Click Import
  10. Click OK for the warning about the trust path.
  11. Click OK when it displays the details about the certificate.
  12. Click Yes to accept the certificate as trusted.
  13. When it asks for an alias click OK and click OK again when it says it has imported the certificate.
  14. Click save. Don’t forget this or the change is discarded.
  15. Copy the file cacerts back where you found it.

On Linux:

You can download the SSL certificate from a web server that is already using it like this:

$ echo -n | openssl s_client -connect | 
   sed -ne '/-BEGIN CERTIFICATE-/,/-END CERTIFICATE-/p' > /tmp/examplecert.crt

Optionally verify the certificate information:

$ openssl x509 -in /tmp/examplecert.crt -text

Import the certificate into the Java cacerts keystore:

$ keytool -import -trustcacerts -keystore /opt/java/jre/lib/security/cacerts 
   -storepass changeit -noprompt -alias mycert -file /tmp/examplecert.crt

    D:Javajdk1.5.0_10binkeytool -import -file "D:CertificatesSDS" -keystore "D:Javajdk1.5.0_10jrelibsecuritycacerts" -alias "sds certificate"

I ended up writing a small script that adds the certificates to the keystores, so it is much easier to use.

You can get the latest version from

# version 1.0

KEYTOOL="sudo keytool"

# /etc/java-6-sun/security/cacerts

for CACERTS in  /usr/lib/jvm/java-8-oracle/jre/lib/security/cacerts 

if [ -e "$CACERTS" ]
    echo --- Adding certs to $CACERTS

# FYI: the default keystore is located in ~/.keystore

if [ -z "$REMHOST" ]
    echo "ERROR: Please specify the server name to import the certificatin from, eventually followed by the port number, if other than 443."
    exit 1

set -e


if openssl s_client -connect $REMHOST:$REMPORT 1>/tmp/keytool_stdout 2>/tmp/output </dev/null
        cat /tmp/keytool_stdout
        cat /tmp/output
        exit 1

if sed -ne '/-BEGIN CERTIFICATE-/,/-END CERTIFICATE-/p' </tmp/keytool_stdout > /tmp/$REMHOST:$REMPORT.pem
        echo "ERROR: Unable to extract the certificate from $REMHOST:$REMPORT ($?)"
        cat /tmp/output

if $KEYTOOL -list -storepass ${KEYSTORE_PASS} -alias $REMHOST:$REMPORT >/dev/null
    echo "Key of $REMHOST already found, skipping it."
    $KEYTOOL -import -trustcacerts -noprompt -storepass ${KEYSTORE_PASS} -alias $REMHOST:$REMPORT -file /tmp/$REMHOST:$REMPORT.pem

if $KEYTOOL -list -storepass ${KEYSTORE_PASS} -alias $REMHOST:$REMPORT -keystore "$CACERTS" >/dev/null
    echo "Key of $REMHOST already found in cacerts, skipping it."
    $KEYTOOL -import -trustcacerts -noprompt -keystore "$CACERTS" -storepass ${KEYSTORE_PASS} -alias $REMHOST:$REMPORT -file /tmp/$REMHOST:$REMPORT.pem




This worked for me. 🙂

sudo keytool -importcert -file filename.cer -alias randomaliasname -keystore $JAVA_HOME/jre/lib/security/cacerts -storepass changeit 

You can use keytool with your Java installation which should be in $JAVA_HOME/bin. The Java keystore is located in $JAVA_HOME/lib/security/cacerts or $JAVA_HOME/jre/lib/security/cacerts which depends on if you have the JDK or JRE installed.

If using Java 9 or later, you don’t need to know the exact location. You can use the -cacerts option as a shortcut.

Java 9+

So with Java 9 (aka Java 1.9) or later, simply use

keytool -importcert -trustcacerts -cacerts -file myCert.pem -alias myCert

Earlier Java versions

With Java 8 (aka 1.8) or older, you must specify the keystore location like so

keytool -importcert -trustcacerts -keystore $JAVA_HOME/lib/security/cacerts -file myCert.pem -alias myCert

With Java 5 (aka 1.5) or older, the -importcert option did not exist. It was called -import, but otherwise it’s identical. So use

keytool -import -trustcacerts -keystore $JAVA_HOME/lib/security/cacerts -file myCert.pem -alias myCert

Additional options

  • You will be asked for the truststore password, The default password is changeit.
  • If you need to run the import unattended, you can add -storepass changeit -noprompt


keytool can import X.509 v1, v2, and v3 certificates, and PKCS#7 formatted certificate chains consisting of certificates of that type (P7B). The data to be imported must be provided

  • either in binary encoding format (DER)
  • or in printable encoding format (aka base64 encoded), enclosed in -----BEGIN and -----END lines (PEM)

Note: I’m not sure if certificate chains in PEM format really work.

Bonus script

I’m afraid, it’s bash, so no solution for Windows users.

This simple script, created thanks to several useful questions and smart answers here on stackoverflow, checks the Java version and – if necessary – determines the correct keystore location, and it can import multiple certificates in one command. Note that you must pass the file pattern argument in single quotes (see usage).


# Add custom root certificates to Java trust store

if [ "$#" -ne 1 ]; then
    SCRIPT=`basename "$0"`
    echo "Usage: $SCRIPT 'path/to/certs/*'"
    exit 1


JAVA_VERSION=`java -version 2>&1 | head -1 | cut -d'"' -f2 | sed '/^1./s///' | cut -d'.' -f1`

if (( $JAVA_VERSION >= 9 )); then
    # Check where cacerts are located
    # differs depending or jdk or jre installed
    if [ -d "$JAVA_HOME/jre" ]; then
    CACERTS="-keystore $CACERTS/lib/security/cacerts"   

# Now add certificates 
    # Remove path, then suffix to derive alias from filename
    $JAVA_HOME/bin/keytool -importcert -file "$CERTFILE" -alias "$ALIAS" $CACERTS -trustcacerts -storepass changeit -noprompt
    if [ $? -ne 0 ]; then
        echo "Failed to add $CERTFILE as $ALIAS to $CACERTS"
        exit 1

If you are using a certificate signed by a Certificate Authority that is not included in the Java cacerts file by default, you need to complete the following configuration for HTTPS connections.
To import certificates into cacerts:

  1. Open Windows Explorer and navigate to the cacerts file, which is located in the jrelibsecurity subfolder where AX Core Client is installed. The default location is C:Program FilesACL SoftwareAX Core Clientjrelibsecurity

  2. Create a backup copy of the file before making any changes.

  3. Depending on the certificates you receive from the Certificate Authority you are using, you may need to import an intermediate certificate and/or root certificate into the cacerts file. Use the following syntax to import certificates:

    keytool -import -alias <alias> -keystore <cacerts_file> -trustcacerts -file <certificate_filename>

  4. If you are importing both certificates the alias specified for each certificate should be unique.

  5. Type the password for the keystore at the “Password” prompt and press Enter. The default Java password for the cacerts file is “changeit”.
    Type ‘y’ at the “Trust this certificate?” prompt and press Enter.

Fist get the certificate from the provider. Create a file ends with .cer and paste the certificate.

Copy the text file or paste it somewhere you can access it then use the cmd prompt as an admin and cd to the bin of the jdk; the command that will be used is the: keytool

Change the password of the keystore with:

keytool -storepasswd -keystore "path of the key store from c and down"

The password is : changeit

Then you will be asked to enter the new password twice. Then type the following:

keytool -importcert -file "C:Program FilesJavajdk-13.0.2libsecuritycertificateFile.cer" -alias chooseAname -keystore  "C:Program FilesJavajdk-13.0.2libsecuritycacerts"

The simple command ‘keytool’ also works on Windows and/or with Cygwin.

IF you’re using Cygwin here is the modified command that I used from the bottom of “S.Botha’s” answer :

  1. make sure you identify the JRE inside the JDK that you will be using
  2. Start your prompt/cygwin as admin
  3. go inside the bin directory of that JDK e.g. cd /cygdrive/c/Program Files/Java/jdk1.8.0_121/jre/bin
  4. Execute the keytool command from inside it, where you provide the path to your new Cert at the end, like so:

    ./keytool.exe -import -trustcacerts -keystore ../lib/security/cacerts  -storepass changeit -noprompt -alias myownaliasformysystem -file "D:Stuffsaved-certsca.cert"

Notice, because if this is under Cygwin you’re giving a path to a non-Cygwin program, so the path is DOS-like and in quotes.

Might want to try

keytool -import -trustcacerts -noprompt -keystore <full path to cacerts> -storepass changeit -alias $REMHOST -file $REMHOST.pem

i honestly have no idea where it puts your certificate if you just write cacerts just give it a full path

install certificate in java linux

/opt/jdk(version)/bin/keytool -import -alias aliasname -file certificate.cer -keystore cacerts -storepass password

cd C:Program FilesJavajre1.8.0_301libsecurity
keytool -import -trustcacerts -alias cert_ssl -file C:optesb-configkeystorescert.cer -noprompt -storepass changeit -keystore cacerts

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